Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é o menor valor de joined?
 ###Tabelas: CREATE TABLE mixed_doubles (mixed_doubles_id AUTO_INCREMENT PRIMARY KEY, Tournament VARCHAR, 1989 VARCHAR, 1990 VARCHAR, 1991 VARCHAR, 1992 VARCHAR, 1993 VARCHAR, 1994 VARCHAR, 1995 VARCHAR, 1996 VARCHAR, 1997 VARCHAR, Career W–L VARCHAR) CREATE TABLE 2011_draft_picks (2011_draft_picks_id AUTO_INCREMENT PRIMARY KEY, Round INT, Overall VARCHAR, Player VARCHAR, Position VARCHAR, Nationality VARCHAR, Club team VARCHAR) CREATE TABLE 3500-series_"bloomfield" (3500-series_"bloomfield"_id AUTO_INCREMENT PRIMARY KEY, model VARCHAR, Speed (GHz) VARCHAR, L3 Cache (MB) INT, QPI speed (GT/s) VARCHAR, DDR3 Clock (MHz) INT, TDP (W) INT, Cores INT, Threads INT, Turbo-Boost VARCHAR) CREATE TABLE current_members (current_members_id AUTO_INCREMENT PRIMARY KEY, Institution VARCHAR, Location VARCHAR, Nickname VARCHAR, Founded INT, Type VARCHAR, Enrollment INT, Football? VARCHAR, Joined INT) CREATE TABLE current_agr_reactors (current_agr_reactors_id AUTO_INCREMENT PRIMARY KEY, AGR Power Station VARCHAR, Net MWe INT, Construction started INT, Connected to grid INT, Commercial operation INT, Accounting closure date INT)  
SELECT MIN Joined FROM current_members